Sulphur-containing phosphatide, lubricant, and method of making



Patented Nov. 25,1947

SULPHUR-CONTAINING PHOSPHATIDE, LU-

BRICANT, AND METHOD OF MAKING Edward Trueger, Roselle, N. J assignor to American Lecithin Company, Cleveland, Ohio, a corporation of Ohio No Drawing. Application September 3, 1943,

Serial No. 501,178

7 Claims. (01. 25249.9)

Mineral lubricating oils and greases are not capable of withstanding certain severe operating conditions to which they are often subjected in use, for example, in internal combustion engines, electric motors, high pressure bearings and the like. These oils and greases tend to deteriorate or decompose under some of those conditions.

In use, these oils and greases may deteriorate by being oxidized with the resultant formation of corrosive acids which corrode-certain metals and alloys, particularly bearing metal containing cadmium-silver or copper-lead alloys.

strength alloys are required to carry heavy loads. These oils and greases may also deteriorate or decompose by being cracked, or oxidized, and

then polymerized with resultant increase of vis- M cosity or formation of resinous compounds, or

both. Excessive wear of engine parts, loss of engine power and the sticking or freezing of metal parts, such as rings in piston'ring grooves, and increased costs of engine operation and maintenance may result from these increases in viscosity or formations of resinous compounds.

Various efforts have been made heretofore to increase the resistance of lubricating oils and greases to deterioration or decomposition when subjected to severe operating conditions. These efforts have included the use of additives, that is, compounds which were added to the oils and greases and which consisted of phenols, halogenated materials, phosphorous, metallic compounds and commercial soybean lecithin. However, so far as I know, none of these additives has been entirely satisfactory.

The present invention is predicated on the discovery that phosphatides in their commercial form or purified forms, and their lecithin and cephalin fractions, possess new and unexpected inhibiting properties when combined with sulfur.

While various methods may be employed to produce the compounds embodying this invention, one convenient method which is satisfactory is as follows: Commercial soybean phosphatide was dehydrated by dissolving it in benzene and distilling off the water. The phosphatides were reacted at room temperature with thiocyanogen in solution, for example, a .2N solution in benzene,

Such corrosion may be of critical importance wherehigh with the formation of a sulfur-containing phosphatidic compound. The solvent was removed after completion of the reaction and the compound remaining was ready for use as an inhibiting additive for a mineral lubricating oil or grease.

The amount of sulfur combined with the phosphatide may be varied by varying the ratio of phosphatide to thiocyanogen or by varying the strength of the thiocyanogen solution but the latter method is not preferred because of the decrease in stability of the thiocyanogen as its concentration increases. When about 68.8 gms. of dehydrated phosphatide was treated with about 400 cc. of .2N thiocyanogen solution the resulting compound contained about 3.73%of sulfur. A smaller amount of the phosphatide when treated with the same amount of solution gave a compound containing 5.43% of sulfur. By varying the reactants, as described, sulfur contents in the resulting compounds may range up to about 10% or more.

Phosphatides containing below about 4% of sulfur are soluble in mineral lubricating oils but as the sulfur content increases beyond about 4% the solubility of the compounds decreases. However, the compounds which are insufficiently soluble in the oil may be used satisfactorily with greases.

One method of preparing the above mentioned thiocyanogen solution is as follows:

Chemically pure potassium thiocyanate and chemically pure lead nitrate were reacted in benzene and the resulting lead thiocyanate was carefully dried. A thiocyanate solution was prepared by dissolving 10 gms. of bromine in 300 cc. of benzene and adding thereto 30 gms. of the dried lead thiocyanate. The excess lead thiocyanate and the resulting lead bromide were filtered off. The filtrate consisted of a benzene solution of fairly stable thiocyanogen having a thiocyanogen normality of .215N, as determined by titration against a standard sodium thiosulfate solution.

The inhibiting properties of compounds embodying the present invention are illustrated by the following test results: An SAE-30 Mid-Continent, solvent refined, lubricating oil having dissolved therein about .5% of phosphatide compound containing about 3.73% of sulfur was subjected to the Sohio test for hours. The resulting naphtha insolubles (mgs./10 gms. oil) amounted to about 22 mgs. as compared with about 40 mgs. for the same oil containing the same amount of untreated phosphatide as an additive. Moreover, this sulfur containing phosphatide appeared to exert a greater anti-corrosive action than phosphatide materials free from sulfur. A similar phosphatide containing about 5.43% of sulfur also possessed good inhibiting properties under similar test conditions.

Variouszamounts of. sulfur-containing phosphatides may be used-with mineral oil lubricants. When used with oils they should be largely or wholly soluble therein, but when used with greases they may be largely or wholly insoluble. The phosphatides containing up to about6%:ofsulfur are soluble in such oils and may amount toes much as 5% of the oils while phosphatides-1 containing above about 6% of sulfur'arei'largelyzinsoluble in such oils, may be used effectively in greases and may amount tomas much as..15% thereof.

The Sohio test, above referred to, was carried out as follows: Air was blown at a constant rate thru the lubricating oil while it was maintained at ran elevated temperature and r contained i cat- I-EtllZeIS in" the form of two lovrcarbon. steel tubes and a copper strip immersediint'he 'oil. The standard conditions *oftthe' test 1 were 'as follows:

Temperature "F "325 Volume. of, nil ec 255 Air rate liters 'per hour 30 "Area'of Steel q.'. 300 Area 'oficopper "em 20 Time, variable.

wHaving thus-described the invention so that others skilled inthe-art maybe-ablelto under- ;:stand and practice the -same,. I 'state .lt-hat what -use-as -additives*to-a lubricant containing a, min- -eral oil to" inhibit the formation of naphtha in- ,solubles 'therein whichcomprises the .steps of treating a vegetable phosphatide with an approxi- *mately .-.2Nsolution of thiocyanogenlinlbenzene at roomtemperature, and removing. the i. benzene after formation 4 of the 1 resulting. .sulfurecontain- .ing phosphatide compound.

2. The process for treating phosphatides for use as additives to alubricant, containing. a mineral oil to inhibit the formation of naphtha Jin- :solubles thereinwhich comprises the stepoibringing a vegetable phosphatide into -contact with ithiocyanogeni dissolved in an .Or anic solvent.

3. The process for treating phosphatides for use as additives to a lubricant containing a mineral oil to inhibit the formation of naphtha insolubles therein which includes the step of contacting a vegetable phosphatide with dissolved 1 thiocyanogen.

.4. 1. Almineral lubricating composition. comprising a mineral oil and between about .1% and about 15% of a product prepared by reacting a crude vegetable phosphatide with thiocyanogen at room temperature.

"A'mineral lubricating composition compris- :ingrai. mineral oil and between about .1% and, about 5%rfof.a;-product prepared by reacting a vegetablezphosphatide with thiocyanogen in suitable, diluent at room temperature.

6. 1 A mineral lubricating composition comprising a mineral oil and about 5% of a product prepared by reacting a vegetable phosphatide with thiocyanogen in a suitable diluent at room temperature.

7... A- mineral l lubricating composition compris- "ing a mineral oil and between about -,1%-and about 5%-of aproduct prepared by reacting a .crude vegetable phosphatide with a'0.2 normal benzene-solution :of thiocyanogenat. room temperature. V

EDWARD TRUEGER.

REFERENCES CITED The following"references are -.:6f record: in; the filerof this patent:

UNITED STATES PATENTS "OTHER, 1 REFERENCES .Jamieson, fVegetable .Iats .and .Oils, Q1943,

. pages 395. to 398.

The Soybean Industry, rI-IoWath .(page .108), ChemicalPublishing Co. of N. Y.,i19'38. 

